As the days passed, David, who is 37, started to develop other symptoms.

His vision started to go blurry, his hearing began to go, he had tinnitus constantly and his concentration and memory were also affected.

He said: “One of the very odd symptoms that people with CSF leak get is this odd feeling that your brain is being pulled down your spine.

“It’s a very hard symptom to express to somebody that hasn’t felt it.

“It’s a kind of unrelenting pressure, as if there is bricks on your head, pushing your brain down.”

Doctors have since tried unsuccessfully to treat David’s CSF leak, which is thought to be somewhere on his upper spine.

He has also been treated in Los Angeles by Dr Wouter Schievink, the same surgeon that successfully treated George Clooney’s condition.

‘Back with a vengeance’

However, David is yet to resume his former life and says since developing CSF leak, he has lost his job and found that the only way he can get relief is by lying down.

“When you’re lying down, you don’t have [the symptoms] or they’re much reduced,” he said.

“But as soon as you sit up or stand up, they come back with a vengeance.

“It is that element that makes it such a disabling condition and you just can’t live your life like that.”

David said that was one of the cruellest elements of CSF leak.

He said: “You can feel like you can get up and go to work, you can live your life.

“But as soon as you sit up, it’s like an egg timer, it’s only a matter of time before these horrific symptoms come back and force you back to bed again.

“It’s a very tough one to live with. It’s very disabling for many people and for most it’s certainly very life-changing.”

Image caption
David was treated by Dr Wouter Schievink, who also treated George Clooney

In the past two and a half years, David has left home no more than 10 or 15 times and most of that has been on a stretcher or in an ambulance to go for treatment or scans.

After first developing his life-changing headache, it took three months for David to be diagnosed.

However, he was one of the lucky ones. On average Scots with CSF leak face a 13-month wait before they know what is wrong with them.

James Walkden, a neurosurgeon who is now helping to treat David, said there was much to be done to educate medical staff on CSF leak.

‘Early stage’

He said: “I have to say the teaching about this condition at medical school and even at post-graduate is zero.

“It’s really only a small sub specialist area of neurosurgery or neurology that even recognises this condition and that’s why unfortunately there’s often multiple visits to medical professionals, multiple mis-diagnosis before they reach somebody who does understand this condition.

“But by then months have turned into years and your success rate of the investigations and the treatment diminishes as time goes on.

“So, it’s not that we’re stumped, it’s unfortunately recognition of this condition at an early stage and getting the person to the right department with the right expertise.”

More information about the condition is available at the CSF Leak Association.